1. Field of the Invention
The present invention relates to oil reservoir production techniques using secondary or tertiary enhanced recovery, wherein a polymer-based fluid is injected to sweep the porous medium to improve production. The invention more particularly relates to a method of simulating this enhanced recovery technique.
2. Description of the Prior Art
Reservoir simulators are in use, such as, for example, PUMAFLOW™ (IFP) or Eclipse™ (Schlumberger) that help optimize production schemes and assess the efficiency of hydrocarbon recovery techniques. Most of these simulators integrate “Polymer” program modules that account for, among other things, the mobility reduction Rm that represents the apparent viscosity of the polymer in the reservoir, and the permeability reduction Rk. It is however known that reservoir simulators, which are computer-based, are provided with a “Polymer” option account for the mobility reduction determined in a situation of residual oil saturation (SOR).
Conventionally, polymer injection into a given porous medium (reservoir facies) in a situation of residual oil saturation (SOR) is carried out in the laboratory. The mobility reduction and the permeability reduction are thus determined for the facies being considered, and the adsorption is quantified. These parameters are determined at this saturation (SOR) by postulating that, for a mobility ratio M close to 1 (M=kw/μw)/(ko/μo), the dispersion of the saturation front is low and the sweep can be compared to a piston-type displacement. All of the data acquired at the end of the laboratory experiments are used as input data for the reservoir model. The various parameters are input into the simulators in a form of charts giving Rm as a function of the polymer concentration. The zero polymer concentration is given by the value of Rk.